Detecive Don Flack knows the streets of New York. Yonkers-bred, descended from a long line of police officers, Detective Flack never questioned his future. Working closely with Mac Taylor and his unit, Detective Flack bridges the gap between the old-school NYPD and the new generation of CSI. Carrying with him an intense hatred of the "bad guy," his approach to solving crimes, while sometimes borderline, is nonetheless always effective.